Fabry-Perot interferometer is a multiple beam interferometer, which could accurately measure wavelength of incident light and perform a wide role in scientific research, manufacture and teaching. The Fabry-Perot interferometer could be build by scientific research institutions, factories, schools or the like themselves for measuring wavelength of incident light due to its simple structure and easy-to-use.
The Fabry-Perot interferometer includes a Fabry-Perot cavity and a lens. FIG. 1 is a schematic diagram of a Fabry-Perot cavity in prior art. As shown in FIG. 1, the Fabry-Perot cavity includes two parallel glass substrates M and M′ whose inner surfaces facing with each other are coated with a coating with high reflectivity. In practical use, an incident light enters through M, reflects between the two parallel glass substrates several times, and is focused by a convex lens (not shown in FIG. 1), finally multiple-beam interference fringes are generated. In order to meet interference condition, optical path difference between two adjacent light beams is required to be an integral multiple of wavelength. Consequently, optical path difference could be adjusted to meet interference condition of light beams with various wavelengths, from this the wavelength of incident light could be determined. A concrete method for adjusting optical path difference is to adjust a mechanical platform under the Fabry-Perot interferometer, thusly adjusting a distance between the two parallel glass substrates, and adjusting the optical path difference accordingly, which could allow light with various wavelengths to interfere.